Herbicide faces de-regulation if growers don’t start acting.
24 Feb 2021
By Paul Goddard, Stewardship and Value Chain Manager at BASF
Post-emergence options in peas and beans are extremely limited so protecting the chemistry we do have is vital for the future of these crops. However, one product is under threat as it approaches reapproval in 2025 with drastic action required by growers now, in order to safeguard its future.
In our latest blog, we speak to Paul Goddard, Stewardship and Value Chain Manager at BASF to find out more about bentazone, one of the few post-emergence herbicides for beans and the only post-em available for some especially challenging weeds in the pea crop, such as black nightshade, for four decades.
Over the last five years, we have all witnessed the UK’s unprecedented adverse weather, with floods, droughts and storms. In addition, there has been a greater focus on sustainable rotations and how we improve our soil structure. As a result, many growers have reintroduced pulses into their rotation, some after a long break, or are growing pulses for the very first time.
This raises concerns that bentazone use is increasing across the UK. The herbicide is currently, and has been for nearly four decades, one of the few post-emergence options available for peas and beans. It is also commonly used on linseed, alliums and potatoes.
The chemistry is absorbed through the leaves of target plants, disrupting the photosynthesis and causing a reduction in the carbohydrate reserves. However, it is highly soluble in water and mobile in soil. As such, bentazone has been detected in both ground and surface water for many years and whilst BASF and the wider agricultural industry has had a stewardship programme in place from 2014, we have yet to see a serious decline in the levels detected.
This may be, in part, down to the time it takes for the chemistry to get through to the extraction point. In some cases, the groundwater can also rise to become surface water, e.g. as springs; but there is still more growers could be doing.
Last year, we commissioned some work focusing predominantly on groundwater and the likely sources at a number of the most challenged extraction points. At three of the five locations, a point-source is the likely cause. For the other two, point-source cannot be eliminated and therefore is a factor.
As bentazone can enter the water courses through both groundwater and surface, there are multiple chances for leaching so we must do everything we can culturally, and chemically, to reduce the levels.
How and where we fill the sprayer can play a significant role. Most growers now have a dedicated area of concrete that can easily be cleaned when using the granular formulation. For those using liquid, we have been working with industry partners to develop the new EasyConnect closed transfer system which, after rigorous testing, will be available to the market shortly. During 2022/23 a broad range of containers (IS 63 Industry Standard) will be equipped with the standardised pre-mounted screw cap, compatible with the system.
Bentazone is due review for re-approval in 2025. The Environment Agency will be part of the decision panel and has made it very clear that the industry must bring levels and numbers of detects in water down. As an industry we need to be showing an active stewardship programme with bentazone users actively participating. If we don’t, the decision will be made for us which will have a detrimental impact on the future of some crops.
There are a number of things growers can do to help:
1. Ensure the field is suitable before planting the crops.
Shallow, stony soils on chalk, limestone, or sandstone allow water to move more readily taking the chemistry with it. Likewise, low organic matter soil matter is a challenge as there is less to bind the soil and chemistry together.
2. Avoid high risk areas.
You can download Magic Maps from Natural England or Check Zones from UK Gov which provide geographic information about the natural environment including the water courses, highlighting high risk areas; the Safeguard Zones and Source Protection Zones for bentazone.
3. Keep chemistry on the surface.
Bentazone will breakdown quickly where there is good light and oxygen so by keeping it on the surface you limit the chance of transfer whilst still protecting your crops. Avoid spraying if heavy rain is forecast in the following two days.
4. Consider the weather.
We know farming faces many pressures, but it is important to avoid spraying your crop on wet days or when there is significant water sat in the field (fields with a shallow water table are to be avoided). The chemistry has high solubility and mobility so it will move into the water course or groundwater.
5. No spray zone.
Having a 6m buffer zone/5m no spray zone around the edges of the field, will help where there are high risk areas.
From 2027 water companies are unable to deploy new water treatment and, as a result from the natural filtration, there is a lot less on groundwater abstractions. Cleaning water is expensive, both in time and finances, which we all as customers ultimately pay for. Avoiding pollution is not only better for our crops as they retain more of the chemistry where it is needed to work, but there is a benefit for each and every one of us as consumers.
The “Better Bentazone Together” campaign is an industry initiative to raise awareness for bentazone stewardship to reduce the detects in water. We are working with the Environment Agency and water companies, developing drip trays, managing point sources and aligning our labels so we can continue to offer guidance and support to growers.
But there is only so much we can do as manufacturers. Securing the future of bentazone has got to come from the field - it doesn’t matter if you grow 10ha or 100ha, every person who is applying bentazone has a responsibility to maintain high levels of stewardship and help increase water quality. Together we will make the difference.
To find out more about Better Bentazone Together stewardship, click here.
For PGRO’s top tips growing a successful spring bean crop, click here.